Zinc Chloride Precursors Research Articles

Physical properties of spray pyrolysed ZnO thin films obtained from nitrate, acetate and chloride precursors: Comparative study for Solar Cell Applications

ZnO thin films prepared using zinc chloride, zinc acetate and zinc nitrate precursors have been successfully synthesized by Spray Pyrolysis method. Films depositions were carried out on glass substrates at 350◦C. Structural properties of ZnO films were investigated by X-ray diffraction (XRD), confirming that all precursors have an Hexagonal Wurtzite structure. The obtained films were oriented along the preferential (002) crystallographic plane. The phase purity was also confirmed by X-ray photoelectron spectroscopy (XPS), Ultra Violet-Visible, and Energy Dispersive X-ray spectroscopy measurements (EDX). The optical measurement revealed that films have average transmittance of 58%, 78% and 65% for zinc chloride, zinc acetate and zinc nitrate, respectively. The band gap values obtained are 3.19, 3.17 and 3.23 eV for ZnO films using zinc acetate, zinc chloride and zinc nitrate precursors, respectively. Additionally, the refractive index and extinction coefficient of the ZnO films for all precursors have been explored.

Comparative Studies on Synthesis, Characterization and Photocatalytic Activity of Ag Doped ZnO Nanoparticles.

In this work, silver (Ag) doped zinc oxide (ZnO) nanoparticles were synthesized using zinc chloride, zinc nitrate, and zinc acetate precursors with (0 to 10) wt % Ag doping by a simple reflux chemical method. The nanoparticles were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet visible spectroscopy, and photoluminescence spectroscopy. The nanoparticles are studied as a photocatalyst for visible light driven annihilation of methylene blue and rose bengal dyes. The 5 wt % Ag doped ZnO displayed optimum photocatalytic activity toward methylene blue and rose bengal dye degradation at the rate of 13 × 10-2 min-1 and 10 × 10-2 min-1, respectively. Here we report antifungal activity for the first time using Ag doped ZnO nanoparticles against Bipolaris sorokiniana, displaying 45% efficiency for 7 wt % Ag doped ZnO.

Liquefied petroleum gas sensing performance of solochemically synthesized ZnO nanorods: Role of precursors and fractal analysis

Nanorods of ZnO were grown successfully using a template free solochemical route using zinc chloride, zinc nitrate and zinc acetate precursors at 70 °C. The structural and morphological analysis of synthesized all ZnO samples were tested by X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission electron microscopy (TEM) techniques. Whole pattern fitting of XRD patterns shows less strain in unit cell is observed in case of ZnO sample synthesized from zinc chloride precursor. Variations in aspect ratios of ZnO nanorods synthesized using different precursors were observed from TEM results. The ZnO nanorods composed thin films were fabricated via spin coating technique and its liquefied petroleum gas (LPG) sensing performance was investigated. The surface topographical studies and fractal analysis of these films were examined by atomic force microscopy (AFM). These results reveals that thin film composed ZnO nanorods prepared using zinc chloride precursor possess average roughness ~133 nm and fractal dimension ~ 2.42, which is higher than other films. This film exhibits maximum gas response ~502 towards 50 ppm LPG, along with low response and recovery time, repeatability, great selectivity as compared with thin films synthesized from other precursors. The reason of enhancement of gas response for ZnO thin film synthesized using precursor zinc chloride as compared to zinc acetate and zinc nitrate is explained on the basis of aspect ratio and fractal roughness. The LPG sensing mechanism towards ZnO nanorod is also discussed. • ZnO nanorods are prepared by a simple and low-cost solochemical method. • Excellent LPG performance of spin- coated films using ZnO nanorods explored. • Effect of precursors on LPG sensing and fractal analysis evaluated. • The sensor exhibits a fast response (~6–7 s) and a quick recovery (~6–7 s). • Role of precursors during gas sensing performance assessed on the basis of fractal analysis.

Biosynthesis, characterization, and antibacterial activity of ZnO nanoaggregates using aqueous extract from Anacardium occidentale leaf: comparative study of different precursors

BackgroundVarious parts of Anacardium occidentale plant possess curative qualities like antidiabetic, anti-inflammatory, antibacterial, antifungal, and antioxidant. Aqueous extract of this plant leaf was used in biosynthesizing zinc oxide (ZnO) nanoaggregates using two precursors of zinc salt (zinc acetate dihydrate [Zn(CH3COO)2∙2H2O] and zinc chloride [ZnCl2]). The synthesized ZnO samples were used in a comparative study to investigate the antibacterial activity against selected Gram-positive and Gram-negative microbes [Staphylococcus aureus, Exiguobacterium aquaticum (Gram +ve) and Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii (Gram −ve)]. The synthesized ZnO nanoaggregates from the two precursors were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive x-ray spectroscopy (EDX) techniques.ResultsMicrographs of SEM and TEM confirmed nanoparticles agglomerated into aggregates. While spherical nanoaggregates were identified in samples prepared from Zn(CH3COO)2∙2H2O, flake-like structures were identified in samples synthesized from ZnCl2. Particle size determined by TEM was 107.03 ± 1.54 nm and 206.58 ± 1.86 nm for zinc acetate dihydrate and zinc chloride precursors respectively. ZnO nanoaggregate synthesized using zinc acetate as precursor gave higher antibacterial activity than its counterpart, zinc chloride with K. pneumonia recording the highest inhibition zone of 2.08 ± 0.03 mm (67.53%) whereas S. aureus recorded the least inhibition zone of 1.06 ± 0.14 mm (34.75%) for ZnO nanoaggregate from zinc chloride precursor. Also, antibacterial activity increases with increasing concentration of the extract in general. However, A. baumannii, E. aquaticum, and K. pneumoniae did not follow the continuity trend with regards to the 250 ppm and 500 ppm concentrations.ConclusionBiosynthesis of ZnO nanoaggregates using aqueous extract of A. occidentale leaf from zinc acetate dihydrate and zinc chloride as precursors was successful with the formation of nanospheres and nanoflakes. The study suggested that A. occidentale sp. could be an alternative source for the production of ZnO nanoparticles and are efficient antibacterial compounds against both Gram +ve and Gram −ve microbes with its promising effect against infectious bacteria.

Facile synthesis of spray pyrolyzed ZnO/NiO nanocomposites thin films

This study reviews ZnO, NiO, and ZnO/NiO nanocomposites thin films deposition using the Spray Pyrolysis Technique (S.P.T). The thin films were deposited onto ordinary glass substrates heated at 500 °C from aqueous solutions of zinc chloride and nickel chloride precursors dissolved in distilled water. The structural, morphological, and optical properties of the ZnO, NiO, and ZnO/NiO thin films have been studied by X-ray diffraction, scanning electron microscopy, Raman spectroscopies, and so on. The optical band gaps are 3.3 and 3.5 eV for ZnO and NiO thin films, respectively obtained by UV–Vis spectroscopy. However, the optical band gaps of ZnO/NiO nanocomposites thin films, are noticeable out of the range (3.4–3.64 eV).

Synthesis and Characterization of Complex from K<sub>4</sub>[Co(SCN)<sub>6</sub>], Zinc(II) Chloride and Quinoline as Electrode Material of K-Ion Battery

Prussian Blue Like (PBL) compounds that are potentially used as K-Ion Battery (KIB) electrodes have been synthesized from zinc(II) chloride and quinoline (Qn) precursors combining melting and direct reaction method. The formed K2[Zn(Qn)2][Co(SCN)6] compounds melt in range 179-181°C with conductivity value reaches 468 μS/cm. Thiocyanate and quinoline ligands were characterized using FT-IR and UV-Vis spectrometry. The cyclic voltammetry of the formed compounds showed the reduction potential up to -0.34 V (versus AgCl/Ag).

The effects of Zn incorporation on electrical, photoluminescence and spectral sensitivity of SILAR deposited CdS thin films

The SILAR deposited CdS films were incorporated with various concentrations of zinc using zinc acetate and zinc chloride precursors. The presence of zinc was found to alter the crystal structure and energy bandgap of the films. The bandgap increased by nearly 44% with the increase of zinc concentration in the films. The photoluminescence spectra of the films revealed the presence of several localized defects levels within the forbidden bandgap. The peak spectral response wavelength was found to vary from 500 nm to 400 nm with the increase of zinc. The photocurrent was found to increase with the Cd:Zn ratio. The films with relatively high concentrations of zinc were found to be better suited for the photodetector applications due to their higher photocurrent to dark current ratio.

Room Temperature Synthesis of Monodisperse ZnO Nanoparticles Using Ultrasonically Atomized Precursor Mist in Simple Chemical Route

Monodisperse zinc oxide (ZnO) nanoparticles were synthesized using ultrasonically atomized precursor mist in simple chemical route at low temperature. Analytical grade sodium hydroxide and zinc chloride were dissolved in 100 ml methanol. Zinc chloride precursor solution was converted into very fine mist (atomized) using a nozzle (Sono-Tek Corporation, U.S.A.) operated at ultrasonic frequency of 120 KHz. Fine mist droplets were added slowly (50ml/ hour) into sodium hydroxide solution in 2 hours. The NaOH solution in beaker turned slowly into white product due to addition of zinc chloride. The white product was kept in constant temperature bath at 90°C for 3 hours. The white product was washed five times using double distill water and dried in oven for 2 hours. Different powder samples were synthesized using same procedure by changing the molarity of sodium hydroxide keeping the molarity of zinc chloride and other preparative conditions same. The structural, microstructural, thermal and optical properties of fine powders were analyzed using X Ray Diffractometer, Scanning Electron Microscopy, Simultaneous Thermal Analyzer, UV-Vis Spectroscopy and Photoluminescence Spectroscopy. Fine ZnO nanorods, elongated and spherical nanoparticles were observed due to change in molarity of NaOH. The results are discussed and interpreted.

Physico-chemical studies of Cd1−xZnxS thin films produced by simple two-electrode electrodeposition system for solar cell application

Cd1−xZnxS thin films have been cathodically electrodeposited on glass/fluorine-doped tin oxide substrates using a low-cost two-electrode configuration with an electrolytic bath containing cadmium chloride, zinc chloride and sodium thiosulphate precursors. The deposition was carried out by varying zinc chloride concentration (0 M, 0.3 M, 0.6 M and 0.9 M) in the deposition electrolyte. The structural, compositional, phonon vibrational, morphological and optical properties of the resulting films have been characterized using glancing incidence X-ray diffraction, energy-dispersive X-ray (EDX) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM) and UV–Vis spectrophotometry respectively. The XRD result indicates the existence of hexagonal structure of Cd1−xZnxS with intensities of the diffraction peaks decreasing as more Zn is incorporated into the film as a result of decrease in deposition rate. EDX results show the presence of Cd, Zn and S in the deposited Cd1−xZnxS thin films. SEM images show uniform and densely packed surface morphology of the films with distinct shaped grains which gradually less distinct as more Zn is incorporated into the films. The optical measurements reveal a significant increase in energy band gap of the Cd1−xZnxS material as more zinc is incorporated into the films and a film thickness decreases with the energy band gap increasing from 2.40 eV for CdS to 2.62 eV for Cd1−xZnxS. These results show that Cd1−xZnxS material can be applied as a better window material for CdTe, CIG(S,Se) and CZTS-based solar cells than CdS.

Importance of precursor type in fabricating ZnO thin films for photocatalytic applications

Here, the importance of choosing an appropriate precursor with right molarity for the fabrication of zinc oxide (ZnO) films by spray pyrolysis for the photocatalytic application is reported. Films were grown on glass substrates by using three different zinc precursors such as zinc acetate, zinc chloride, and zinc acetylacetonate. The structural, morphological, and optical characterizations were performed on the ZnO films. A preferential orientation along (002) plane, crystallite size distribution in the range 21–59nm, and the nanostructures such as nanothorns, hexagonal nanorods, hexagonal layers and elongated grains, were acquired from the characterization studies. Further, the photocatalytic activity was tested using indigo carmine dye, obtaining 100% of dye degradation using the ZnO thin films deposited with zinc acetate, whereas films from zinc chloride and zinc acetylacetonate precursors showed 20% and 10% of degradation respectively.

Effect of Precursors on Key Opto-electrical Properties of Successive Ion Layer Adsorption and Reaction-Prepared Al:ZnO Thin Films

Aluminum-doped zinc oxide (Al:ZnO) thin films were deposited on glass substrates by successive ion layer adsorption and reaction (SILAR) method using different precursors. This inexpensive SILAR method involves dipping of substrate sequentially in zinc solution, de-ionized water and ethylene glycol in multiple cycles. Prepared films were investigated by x-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), optical absorption, photoluminescence (PL), Raman spectroscopy and electrical studies. XRD study confirmed incorporation of aluminum in ZnO lattice with a polycrystalline hexagonal wurtzite structure of the films. The crystallite size determined by the Scherrer equation showed an increase from 28 nm to 35 nm for samples S1 to S4, respectively. SEM study showed smooth morphology with homogeneous distribution of particles. From the AFM images, the surface roughness was found to change according to precursors. For the optical analysis, the zinc chloride precursor showed high optical transmittance of about 90% in the visible range with a band gap value 3.15 eV. The room-temperature PL spectra exhibited a stronger violet emission peak at 420 nm for all the prepared samples. The Raman spectra showed a peak around 435 cm−1 which could be assigned to non-polar optical phonons (E2-high) mode AZO films of a ZnO wurtzite structure. Hall effect measurements showed n-type conductivity with low resistivity (ρ) and high carrier concentrations (n) of 2.39 × 10−3 Ω-cm and 8.96 × 1020 cm−3, respectively, for the film deposited using zinc chloride as precursor. The above properties make the prepared AZO film to be regarded as a very promising electrode material for fabrication of optoelectronic devices.

Growth of ZnO nanorod arrays by one-step sol–gel process

ZnO nanorods are usually formed by two-step method. In the first step, a seed layer is coated on substrate and then the second treatment by hydrothermal method is employed for formation of nanorods. Here, we report that ZnO nanorods can be directly coated on glass substrates by sol–gel dip coating technique without the second treatment. The effect of coating layers on morphological, structural, electrical, and optical properties was studied. According to the cross-sectional SEM images of the produced ZnO nanorods, a seed layer was spontaneously observed. The diameter of the ZnO nanorods was varied between 200 nm and 1 µm with coating thickness. The effect of the zinc nitrate tetrahydrate and zinc chloride precursors on the preparation of the ZnO nanorods was also investigated. And, it was found that the zinc chloride precursor exhibited formation of nanorods on the glass substrates. According to the Hall effect measurements, the ZnO nanorods exhibited mobility as high as 95 cm2 (Vs)−1. The X-ray diffraction and electrical studies indicated that highly pure crystalline ZnO nanorods could be obtained by the one-step solution method.

Optimization of precursor based on optical, structural and magnetic properties of Cu-doped ZnO nanoparticles

Cu doped ZnO nanoparticles were synthesized via co-precipitation method using different precursors like zinc chloride, zinc acetate and zinc nitrate. The crystallite structure, morphology and optical properties were discussed by X-ray diffraction, scanning electron microscopy and UV–visible photo-spectrometer for different precursors. The hexagonal structure was confirmed by X-ray diffraction. The calculated average crystallite size from XRD spectra was low for zinc chloride precursor (22.3 nm) and high for zinc nitrate precursor (26 nm). The strong and transparent behaviour in the visible region of the sample using zinc nitrate precursor is due to the existence of less defects and enhanced crystal size which leads to the industrial applications especially as transparent electrode. The reduction in strain and the better crystallinity effectively depress interstitial defects. The energy gap is varied between 3.65 and 3.75 eV, where zinc nitrate precursor has Eg = 3.65 eV (minimum) and zinc acetate precursor has Eg = 3.75 eV (maximum). The observed higher energy gap using zinc chloride precursor could be attributed to the poor crystallinity and also the formation of the new compound based on Cu and Zn. The low energy gap for zinc nitrate precursor can be attributed to the better crystallinity with increasing grain size. Change in luminescence intensity and magnetization were discussed based on the defects formation and structural parameters.

Facile synthesis of ZnO nanostructures by spray pyrolysis technique and its application as highly selective H2S sensor

ZnO nanorods were facilely grown on glass substrates using spray pyrolysis technique and they were successfully used to detect hydrogen sulfide at room temperature. Desired molar concentration of zinc chloride precursor was optimized to produce high quality ZnO nanorods. The plausible growth mechanism of ZnO nanorods was schematically depicted and analyzed. Further, the influence of transition metal doping (Co, Ni and Cu) on the structural, morphological, optical and hydrogen sulfide sensing properties was investigated. Sensing response of the undoped and doped thin films were also investigated in the presence of eight different vapors. The sensing response indicated the highly selective nature of ZnO nanorods towards hydrogen sulfide. Among the doped elements, Ni-doped ZnO film showed an excellent sensing response of 321 towards 100ppm of hydrogen sulfide with the response and recovery times of 12 and 90s, respectively.

Effect of Composition and Morphology on Sensor Properties of Aerosol Deposited Nanostructured ZnO+In<SUB>2</SUB> O<SUB>3</SUB> Films

The structural characteristics are investigated of nanoheterogeneous films comprising ZnO, In2 O3 and ZnO + In2 O3 composite produced by aerosol spray pyrolysis technique (SPT). The process utilizes water solutions of zinc chloride and indium nitrate precursors. The X-ray diffraction data show that the SPT process results in polycrystalline films of hexagonal wurtzite type ZnO, and In2 O3 crystals of cubic structure. SPT-synthesized ZnO + In2 O3composites contain mixtures of these crystals. The morphology of the synthesized films is studied by scanning electron microscopy as well as the dependence of morphology on the synthesis conditions, specifically the temperature of the aerosol precipitation and the concentration of the precursors in solutions. The characteristics of nucleation and growth of oxide crystals during the synthesis of ZnO + In2 O3 composite films are also considered. The film with the composition 25 wt% ZnO + 75 wt% In2 O3 contains a large number of small crystal aggregates of arbitrary shape with a high density of contacts between the aggregates and are characterized by a homogeneous structure with high dispersion. Such morphology has high specific surface, which favors high sensory response. In addition, in this range of aggregate composition the relationship between the particles of the catalytically active component- ZnO, cleavage of hydrogen molecule, and In2 O3particles with a high concentration of conduction electrons is close to optimal for the maximum sensory effect in the detection of hydrogen.

Spray Pyrolysis Deposition of ZnO Thin Films from Zinc Chloride Precursor Solution at Different Substrate Temperatures

ZnO films were prepared at different substrate temperatures through spraying pyrolysis deposition of zinc chloride precursor onto glass substrate. Substrate temperature affects surface morphology of films and therefore their optical and electrical properties. All films are polycrystalline with Wurtzite crystal structure and preferentially grow along c-axis direction. Formation of ZnO rods start at about 500 °C. The diameter and length of rods deposited at 500 °C are 350–500 and 550–700 nm, respectively. By increasing substrate temperature, film becomes more coverage and diameter of the rods reduces to 250–300 nm but their length increases to 1,000–1,200 nm, respectively. Optical transmission in visible region decreases with increasing substrate temperature. An ultraviolet emission and two visible emissions at 2.82 and 2.37 eV are observed for photoluminescence spectra at room temperature. The resistivity of ZnO films increases with increasing substrate temperature due to surface morphology.

Synthesis of zinc molybdate and zinc phosphomolybdate nanopigments by an ultrasound assisted route: Advantage over conventional method

In the present study, zinc molybdate (ZM) and zinc phosphomolybdate (ZMP) nanoparticles of white color were synthesized using conventional and innovative sonochemical co-precipitation method without any emulsifier. This new class of pigment is environmental friendly which can be used as an alternative to lead, cadmium and chromium pigment which contain carcinogenic species. Zinc chloride and sodium molybdate precursors were used during synthesis of ZM, and ZMP nanoparticles synthesis was accomplished using sodium molybdate, zinc sulfate and potassium dihydrogen phosphate. The synthesized materials were characterized by XRD, FTIR and TEM to determine the structure, the general type of atom bound in the compound and the morphology of the formed compounds respectively. The rapid saturation of the Zn2+ ions takes place during the synthesis of ZM and ZMP nanoparticles due to ultrasonic irradiation, leading to a faster nucleation of ZM and ZMP nanoparticles with improved solute transfer rate. The average particle size is found to be significantly lower in case of ultrasound assisted synthesis compared to conventional precipitation method. The possible reasons are, improved solute transfer rate and rapid nucleation in the presence of cavitations generated by ultrasonic irradiations.

Spray pyrolysis deposition and characterization of highly c‐axis oriented hexagonal ZnS nanorod crystals

Here we demonstrate that highly c‐axis oriented vertically aligned hexagonal ZnS nanorod‐like crystals have been synthesized via a facile and low‐cost spray pyrolysis method. ZnS layers were grown onto soda‐lime glass (SGL), glasses covered with transparent conductive oxides (TCOs: ITO and FTO) and silicon wafer substrates using zinc chloride and thiocarbamide precursors solution and air as carrier gas. The effect of main technological parameters on formation and properties of ZnS nanorods are studied. SEM, XRD, PL and UV‐VIS were applied to characterize the ZnS layers. Dimensions of the ZnS rods are mainly controlled by the deposition temperature, precursor concentration and substrate type. For instance, rods with d = 80–100 nm and l = 450 nm were obtained using ZnCl2 with c = 0.1 mol/L; whereas rods with d = ca. 80 nm and l = 250 nm were produced from ZnCl2 with c = 0.05 mol/L on glass. According to PL study, such defects as sulphur vacancies (Vs) are present in the ZnS samples, and concentration of Vs decreases with increasing the sulphur amount in solution.According to UV‐VIS, all ZnS layers possess high optical transmittance ca. 80% in the visible spectrum region; the Eg of ZnS is 3.7 eV independent of the deposition conditions, corresponding to wurtzite ZnS. ZnS rods produced at 550 and 580 °C show high haze factor values of ca. 90% at 320–350 nm revealing high light scattering ability. Vertically aligned, uniform in size ZnS rods can be directly grown onto glass, TCO and silicon substrates.

Boron and fluorine doped ZnO films obtained from zinc chloride precursor via chemical spray pyrolysis

Both boron (1, 2 and 3 at %) and fluorine (1, 3, 5 and 7 at %) doped zinc oxide thin films (ZnO:B:F) were fabricated using zinc chloride precursor by airbrush spray pyrolysis technique on glass substrates. X-ray diffraction (XRD) measurements show that all ZnO:B:F films have hexagonal wurtzite structure with a preferential growth along the [0 0 2] direction on glass substrates. Scanning electron microscope (SEM) results show that the morphologies of all doped films have a regular hexagonal shape. The optical measurements reveal that ZnO:B:F films have a direct band gap and optical energy gaps are increasing with boron and fluorine concentration. The optical transmittance of B and F doped ZnO films is measured very low due to columnar structure of prepared films. Moreover, it has been observed that the doping of ZnO films with boron and fluorine decreases the electrical resistance, and the lowest resistances of films were observed at 1%B–3%F and 2%B–3%F concentrations.

Growth of ZnO Thin Films by Spray Plasma Technique: Correlation Between Spectroscopic Measurements and Film Properties

Nanostructured ZnO thin films have been deposited on glass substrate at low substrate temperature (200 °C) using the Spray Plasma technique. The zinc nitrate or zinc chloride precursors (droplets) are injected in a low-pressure Ar/O2 radio-frequency inductive discharge. The O2 fraction and the distance between the inductive coil and the substrate holder were varied, and the resulting effect on the deposited film properties was investigated by means of X-ray diffraction, atomic force microscopy, transmittance electron microscopy and UV–visible spectroscopy. It was shown that the c-axis orientation growth depends on these two parameters but not on the precursor nature. The quality of the deposited film is optimal for 5 % O2 in argon when the inductive coil-substrate distance is small. The Ar/O2 plasma was also diagnosed by optical emission spectroscopy. The oxygen atom relative concentration was monitored by optical emission actinometry and the rotational spectrum of OH was recorded to estimate the gas temperature.